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VEGETATION AND 'WILDLIFE The potential for occurrence of plant and animal species listed as threatened or endangered within the existing creek corridor is low (Environmental Science Associates 1993). [� Vegetation The grasslands adjacent to I-ittlejohns Creek were investigated for positive wetland indicators but did not qualify as wetlands (Jones & Stokes Associates, Inc. 1995). As observed during a field visit on May 14, 1995, the steep slopes in the project area were largely unvegetated; however, some patchily distributed weedy vegetation was found including soft chess (Bromus hordea.ceous), ripgut brome (Bromus diandrus), cocklebur (Xanthium stromarium), lippia (Phyla nodiflora), and bermuda grass (Cynodon dactylon). Although some of this sparse vegetation was dominated by hydrophytic vegetation at the toe of the slope, hydric soil and wetland hydrologic conditions were not evident above the ordinary high-water mark. The dominance of hydrophytic vegetation at the lower part of the slope is probably the result of high flows during winter. (Jones & Stokes Associates, Inc. 1995.) Herbaceous riparian vegetation occurred below the ordinary high-water mark. Dominant species include water primrose (Ludwigia peploides ssp. montevidensis) and waterpepper(Polygonum hydropiperoides); parts of these plants float on the water surface. Other dominant species include rice cutgrass (Leersia oryzoides) and baltic rush (Juncus balticus). All four species are classified as obligate wetland plants (Reed 1988). Woody riparian species, consisting of mostly saplings approximately 8-10 feet tail, are scattered throughout the length of the channel (Figure 2-4); they are mainly within 2 feet of the ordinary high-water mark. In May, several willows that were uprooted by the winter floodflows were found blocking the channel. Since the creek channel is subject to ongoing maintenance for flood protection,these trees will probably be removed. The channel's slopes probably lack mature riparian trees and shrubs because of maintenance for flood protection and erosion prevention and as a result of shallow soils. A few larger trees grow outside of the stream channel. Most riparian trees arej willows (Salix sp.),including black willow (Salix goodingii) and arroyo willow(Salix lasiolepis), with two Oregon ash (Fraxinus latifolia), three cottonwood (Populus fremonth), two tree of heaven (Ailanthus altissima), and eight mature valley oak(Quercus lobata). (Jones & Stokes Associates, Inc. 1995.) Wetland Mitigation and Monitoring Plan for the Chapter 2. E)dsting Conditions Austin Road landfil!Expansion. U.S.Army Corps of Engineers File 199400974 n of Stockton 2-3 April 5, 1996 Ci